Internet of Things (IoT) is an emerging paradigm about building a massive internet to link billions of non-living things to make smart decisions for humans and improve their quality of life. For many IoT devices, such as wireless sensor nodes dispersed in the environment, there is not much control over their placements or orientations. Thus, there is a need to develop orientation insensitive antennas that ensure reliable data transmission irrespective of devices’ positions or orientations.
As billions of such IoT devices are required in the future, a low-cost fabrication process suitable for mass manufacturing must be adapted. The antenna in package (AiP) concept is beneficial that the package is utilized to realize the antennas, not only saving space but also reducing the overall cost. For orientation insensitivity, antennas must be near isotropic and even have to maintain their radiation pattern for multi-bands or wide bandwidths in most applications. However, there is a dearth in the literature about design methodologies for near isotropic antennas, particularly for multi-bands near isotropic AiP designs.
Besides, a near isotropic behavior is also important for polarization, particularly for CP antennas. To have simultaneous isotropy in the radiation pattern and circular polarization is challenging.
In the nutshell, this thesis presents theoretical models and derives conditions for wire AiP design for different specifications, single-band, and dual-band near isotropic antennas, null free near isotropic antenna with wide CP coverage, and a full CP antenna with decent near isotropy (with very narrow null beam). The single-band AiP has only 5.05 dB gain variation at WiFi/BLE band and the dual-band AiP has a decent near isotropic radiation property and covers both GSM900 and GSM1800 bands. The theoretical model for null-free near isotropic antenna with wide CP coverage is presented with particle swarm optimization (PSO). The full CP antenna has a measured CP coverage of 82% with a small null in the radiation pattern. The results are promising and indicate that the conditions and methods proposed are useful for the future near isotropic AiP design. Also, this work provides designers flexibility to adjust the AiP design according to their applications.
Zhen Su was born in Hebei, China. She received the B.Sc. degree from the School of Information Science and Engineering, Jinan, China, in 2011, and the M.Sc. degree in integrated circuits design engineering from the Hong Kong University of Science and Technology, Hong Kong, in 2012. She is currently pursuing the Ph.D. degree with the IMPACT Lab, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. Her current research interests include antennas with near-isotropic patterns, antenna-in-package designs, antenna synthesis, flexible antennas, wearable antennas, and reconfigurable antennas.